1. Field of the Invention
The invention relates to a drilling table for a drilling rig, having an accommodation sleeve that can be rotated by means of a rotational drive, for accommodation of a Kelly rod provided with driving contours. The invention furthermore relates to a drilling rig having such a drilling table.
2. Description of the Related Art
For the production of bores having a large diameter, drilling rigs are used that work according to what is called the Kelly drilling method. In this connection, a specially profiled, multiple-telescoping drill rod, called a Kelly rod, is used. With the Kelly rod, the rotational movement or the torque of a drilling drive as well as the vertical movement or the bias forces are transferred to the drilling tool. The length of the Kelly rod and that of the drilling tool determine the maximal drilling depth that can be reached. The drilling drive is mounted on what is called a drilling table, also called a drilling carriage or guide carriage, which is disposed on a leader so as to be vertically displaceable. This leader is firmly disposed on a support device. The advance of the drilling table with the drilling drive, to generate the required bias forces, takes place by way of a cable feed or also by way of a hydraulic feed cylinder.
To transfer the torque as well as the bias forces from the rotational drive onto the Kelly rod that accommodates the drilling tool, this rod is locked in place in an accommodation sleeve of the drilling table by way of driver strips. The accommodation sleeve, which is disposed on the drilling table so as to rotate, is connected with the rotational drive of the drilling table. The driver strips for transfer of torque and bias forces to the Kelly rod are screwed or welded onto the inside wall of the accommodation sleeve.
It is a disadvantage of the known drilling table that the driver strips, which are disposed on the inside of the accommodation sleeve, and which must regularly be checked and/or replaced as the result of wear, are accessible only with difficulty. For disassembly of the driver strips, it is necessary either to climb in under the “floating” drilling table from below or to work by reaching into the accommodation sleeve, which is configured in the form of a hollow shaft, from above. Replacement can be facilitated in that the drilling table is removed from the leader and tilted toward the rear. Significant time expenditure, however, is required for this facilitation.